Working machines such as excavators and loaders having buckets or trenchers for digging or shoveling e.g. earth or stone debris, are commonly provided with one or more teeth, secured to the bucket via an adaptor. The teeth constitute wear parts which are removable from the adaptors so as to enable replacement of worn out teeth with new ones.
To perform digging or shoveling operations, the teeth should be able to penetrate into material such as earth or mud. To this end, the teeth may have an elongated outer shape, and narrowing from an attachment portion adjacent the adaptor (towards the bucket) to a relatively thin tip portion. Hence, at least towards the tip of the tooth, the tooth will assume a tooth-shaped appearance, having two major surfaces converging towards and meeting at the tip of the tooth.
To acquire the desired penetration capacity, the outer shape of the teeth should therefore exhibit a sufficient length and a suitable slimness.
In use, the teeth will be subject to considerable loads and generally to a rough environment. Therefore, the teeth must be strong and robust enough to resist breaking.
Moreover, there is a general requirement that the teeth, being replacement parts, must be available to a reasonable price. This raises a desire to reduce the amount of material used for the tooth. The requirements for an outer shape providing sufficient penetration, the requirements for strength and robustness of the teeth, and the desire to reduce the amount of material are diverging. Hence, it is a challenge to find a successful compromise between the requirements. To this end, a large variety of teeth with different designs have been proposed in the past.
The tooth and the adaptor must include corresponding features for enabling the coupling of the tooth to the adaptor. Such corresponding features are hereinafter referred to as a “coupling”. Such a coupling should enable secure and fixed attachment of the tooth to the adaptor, and should have sufficient strength and robustness so as to resist the forces involved when the tooth is in use.
Moreover, the coupling should desirably allow removal of a worn out tooth from an adaptor, and enable attachment of a new tooth to the same adaptor.
In summary, it is desired that a coupling between a tooth and an adaptor shall fulfil several different requirements.
The need for a well-functioning coupling must be met taking also the general requirements of the tooth as a whole into account, such as those mentioned in the above.
To achieve a suitable coupling between a tooth and an adaptor, it is known to provide the tooth with a cavity extending from an attachment end of the tooth, and to provide the adaptor with a nose portion corresponding to the cavity, such that the tooth may be installed over the adaptor with the nose portion arranged inside the cavity. To secure the tooth to the adaptor, it is known to use an attachment pin, extending through aligned through holes in the cavity of the tooth and through corresponding through holes in the nose portion of the adaptor.
The adapters can be fixed to the blade in different ways, such as welded, they can be part of the blade as a cast nose or the can be mechanically attached. For instance, in mining, three part systems are used wherein the nose portion of the adapter forms part of the blade of the bucket, being a cast nose.
In couplings using an attachment pin, it is desirable to reduce the risk of breakage of the attachment pin when the tooth, in use, is subject to considerable loads.
Another issue with such couplings is that, even if the attachment pin does not break when the tooth is in use, the pin might be deformed. A deformed pin may be very difficult to remove from the through holes of the tooth and the adaptor, and therefore the removal of a worn out tooth from the adaptor may be complicated. Often, in this situation, the pin must be hammered out of the through holes.
This procedure is highly undesired, and to remove the inconvenience thereof, so called hammer-less couplings have been proposed.
In view of the above, it is generally desired to enable a coupling of the type having a cavity and a corresponding nose portion, through which an attachment pin may extend, and which ensures easy application and removal of the attachment pin, preferably by a hammer-less maneuver.
US 2010 0236108 describes an excavator tooth for attachment to a nose (adaptor) via a fastener extending through at least one of the side walls of the tooth. The excavator tooth include side walls having essentially planar nose-engaging interface surfaces formed therein, one surface resisting rotation of the tooth about the longitudinal axis in one direction, and another interface surface resisting rotation of the tooth in an opposite direction.
U.S. Pat. No. 5,709,043 descries an excavating tooth exhibiting bearing faces which are formed to widen significantly as they extend rearward, to provide broad bearing surfaces at the rear ends of the wear member. The bearing faces are placed at obtuse angles to converging walls and to side walls, so as to avoid areas of stress concentration.
A first object of the invention is to provide a tooth which enables coupling of said tooth to the lip of a bucket of a working machine via an adaptor, and which presents an alternative to, or an advantage over prior solutions in respect of one or more of the aspects mentioned in the above.
A second object of the invention is to provide an adaptor which enables coupling of a tooth to the lip of a bucket of a working machine via said adaptor, and which presents an alternative to, or an advantage over prior solutions in respect of one or more of the aspects mentioned in the above.